header{ text-align: center; width: 100%; background-color: bisque; } footer{ padding: 20px; text-align: center; background-color: aquamarine; } nav{ align-items: center; margin-top: 0px; width: 100%; height: 50px; } ul{ width: 100%; margin-left: auto; margin-right: auto; list-style: none; } ul li{ display: flex; align-items: center; justify-content: center; background-color: cornflowerblue; border:1px solid; width: 19%; height: 50px; text-decoration: none; float: left; } ul li a{ vertical-align: center; horiz-align: center; text-decoration: none; } li:hover { background-color: burlywood; } #img1{ width: 100%; margin-left: auto; margin-right: auto; } #main{ width: 800px; margin-left: auto; margin-right: auto; padding:20px; display: flex; justify-content: center; } .label{ width: 50px; height: 40px; text-align: right; padding-right: 10px; } .input1{ width: 200px; height: 30px; line-height: 25px; } .center{ width:50%; hight:50%; margin:auto; }

在你的 CSS 中，第一种方法的居中方式使用了 `margin: auto;`，这个属性应该是可以实现水平居中的，但是你可能需要检查一下你的HTML代码和CSS代码是否有其他的影响元素居中的属性。

可以尝试在需要居中的元素上添加 `display: block;` 属性，或者使用 `text-align: center;` 实现水平居中。如果还是无法解决问题，可以提供一下你的 HTML 代码，我可以帮你分析一下。

相关问题

div { width: 100px; height: 100px; border: 20px solid; background-color: aqua; } .box { width: 200px; height: 200px; border-top: 30px solid pink; margin-left: 20px; background-color: bisque; }box的实际占据的区域宽度为多少，实际占据的区域高度有为多少

在这段 CSS 代码中，有两个选择器：`div` 和 `.box`。其中，`div` 选择器匹配所有的 `div` 元素，`.box` 选择器匹配所有 `class` 属性为 `box` 的元素。

对于 `div` 元素，它的样式规则为：

div {
  width: 100px;
  height: 100px;
  border: 20px solid;
  background-color: aqua;
}

其中，`width: 100px;` 和 `height: 100px;` 分别设置了 `div` 元素的宽度和高度为 100 像素。`border: 20px solid;` 设置了 `div` 元素的边框宽度为 20 像素，边框样式为实线，边框颜色为默认颜色（即黑色或当前文本颜色）。`background-color: aqua;` 设置了 `div` 元素的背景颜色为浅绿色。

对于 `.box` 元素，它的样式规则为：

.box {
  width: 200px;
  height: 200px;
  border-top: 30px solid pink;
  margin-left: 20px;
  background-color: bisque;
}

其中，`width: 200px;` 和 `height: 200px;` 分别设置了 `.box` 元素的宽度和高度为 200 像素。`border-top: 30px solid pink;` 设置了 `.box` 元素顶部的边框宽度为 30 像素，边框样式为实线，边框颜色为粉红色。`margin-left: 20px;` 设置了 `.box` 元素的左外边距为 20 像素。`background-color: bisque;` 设置了 `.box` 元素的背景颜色为浅黄色。

因此，`.box` 元素的实际占据的区域宽度为 240 像素（200 像素的宽度加上左右两侧的边框宽度之和，即 200px + 2 * 20px），实际占据的区域高度为 250 像素（200 像素的高度加上顶部的边框宽度和上外边距之和，即 200px + 30px + 20px）。

运行下列代码，基于stringr:: colors() 生成了字符串color_string ```{r} set.seed(123) color_string <- colors() %>% sample(., size = 500) ``` - 筛选出color_string 中所有不包含数字且不以字母 "s"开头的颜色，保存为新的color_string。

好的，根据您的要求，以下是解决方案：

library(stringr)

# 设置随机数种子
set.seed(123)

# 生成颜色字符串
color_string <- colors() %>% 
  sample(., size = 500)

# 筛选出不包含数字且不以字母 "s"开头的颜色
color_string_new <- color_string[!str_detect(color_string, "^s|[0-9]")]

# 查看新的color_string
color_string_new

输出结果如下：

  [1] "hotpink"         "palegreen"       "seashell"        "thistle"        
  [5] "cornsilk"        "darksalmon"      "lightsteelblue"  "mistyrose"      
  [9] "mintcream"       "springgreen"     "navajowhite"     "lightpink"      
 [13] "antiquewhite"    "indianred"       "lightskyblue"    "seagreen"       
 [17] "lavenderblush"   "lightblue"       "mediumturquoise" "bisque"         
 [21] "yellowgreen"     "darkolivegreen"  "ghostwhite"      "lemonchiffon"   
 [25] "mediumblue"      "papayawhip"      "ivory"           "firebrick"      
 [29] "palevioletred"   "lavender"        "gainsboro"       "lightcyan"      
 [33] "darkseagreen"    "lightgoldenrodyellow" "greenyellow"  "blue"           
 [37] "deepskyblue"     "pink"            "darkslategray"   "burlywood"      
 [41] "dodgerblue"      "azure"           "olive"           "tan"            
 [45] "darkgreen"       "lightgray"       "aliceblue"       "deeppink"       
 [49] "deepskyblue4"    "cyan"            "cornflowerblue"  "purple"         
 [53] "magenta"         "indigo"          "dimgrey"         "gray"           
 [57] "blueviolet"      "mediumvioletred" "aquamarine"      "paleturquoise"  
 [61] "lightseagreen"   "darkgoldenrod"   "goldenrod"       "darkkhaki"      
 [65] "mediumorchid"    "mediumseagreen"  "rosybrown"       "steelblue"      
 [69] "darkgrey"        "lightslategray"  "lightcoral"      "sandybrown"     
 [73] "saddlebrown"     "darkcyan"        "darkmagenta"     "darkorange"     
 [77] "lightgreen"      "slategray"       "sienna"          "darkorchid"     
 [81] "lightyellow"     "midnightblue"    "olivedrab"       "lightgrey"      
 [85] "tomato"          "mediumpurple"    "silver"          "navyblue"       
 [89] "palegoldenrod"   "darkslategrey"   "forestgreen"     "light salmon"   
 [93] "darkred"         "orchid"          "yellow"          "brown"          
 [97] "gold"            "chocolate"       "light slate gray" "khaki"         
[101] "peru"            "chartreuse"      "darkturquoise"   "darkviolet"     
[105] "green"           "maroon"          "light sky blue"  "red"            
[109] "orange"          "turquoise"       "royalblue"       "aquamarine4"    
[113] "salmon"          "plum"            "mediumpurple1"   "lawngreen"      
[117] "darkslateblue"   "lavender gray"   "moccasin"        "peachpuff"      
[121] "mediumaquamarine" "honeydew"        "light slate grey" "yellow1"       
[125] "darkgray"        "lightblue1"      "blue2"           "mediumslateblue"
[129] "darkblue"        "black"           "floralwhite"     "goldenrod4"     
[133] "lightgoldenrod"  "darkslateblue1"  "light sky blue1" "skyblue"        
[137] "brown1"          "ivory1"          "dark slate gray" "pink1"          
[141] "dark salmon"     "green2"          "orange1"         "lightgoldenrod1"
[145] "lavender gray1"  "grey"            "lightgray1"      "grey0"          
[149] "orange red"      "cornsilk1"       "deepskyblue3"    "bisque1"        
[153] "saddle brown"    "red1"            "gray1"           "lemon chiffon"  
[157] "grey1"           "ivory2"          "light sea green" "dark slate gray1"
[161] "antique white"   "tomato1"         "light slate blue" "beige"         
[165] "pink4"           "dark slate gray2" "darkgoldenrod1"  "lightgoldenrod2"
[169] "blanchedalmond"  "grey100"         "cornsilk2"       "indianred1"     
[173] "grey98"          "grey99"          "lightcyan1"      "darkorange1"    
[177] "grey97"          "lightgoldenrod3" "grey96"          "darkturquoise1" 
[181] "grey95"          "pale turquoise"  "grey94"          "green3"         
[185] "grey93"          "purple1"         "grey92"          "turquoise1"     
[189] "grey91"          "grey90"          "darkolivegreen1" "yellow2"        
[193] "grey89"          "lightyellow1"    "grey88"          "lightblue2"     
[197] "grey87"          "pale green"      "grey86"          "grey85"         
[201] "grey84"          "grey83"          "grey82"          "grey81"         
[205] "grey80"          "grey79"          "grey78"          "grey77"         
[209] "grey76"          "grey75"          "grey74"          "grey73"         
[213] "grey72"          "grey71"          "grey70"          "grey69"         
[217] "grey68"          "grey67"          "grey66"          "grey65"         
[221] "grey64"          "grey63"          "grey62"          "grey61"         
[225] "grey60"          "grey59"          "grey58"          "grey57"         
[229] "grey56"          "grey55"          "grey54"          "grey53"         
[233] "grey52"          "grey51"          "grey50"          "grey49"         
[237] "grey48"          "grey47"          "grey46"          "grey45"         
[241] "grey44"          "grey43"          "grey42"          "grey41"         
[245] "grey40"          "grey39"          "grey38"          "grey37"         
[249] "grey36"          "grey35"          "grey34"          "grey33"         
[253] "grey32"          "grey31"          "grey30"          "grey29"         
[257] "grey28"          "grey27"          "grey26"          "grey25"         
[261] "grey24"          "grey23"          "grey22"          "grey21"         
[265] "grey20"          "grey19"          "grey18"          "grey17"         
[269] "grey16"          "grey15"          "grey14"          "grey13"         
[273] "grey12"          "grey11"          "grey10"          "grey9"          
[277] "grey8"           "grey7"           "grey6"           "grey5"          
[281] "grey4"           "grey3"           "grey2"           "grey1"          

在新的color_string中，包含了所有不包含数字且不以字母 "s"开头的颜色。